Knowledge is one of the most important subjects of the science of Kalām. The issue of “knowledge” plays a key role in the knowledge and determination of the principles of Islamic faith and in the efforts to prove what is required to be believed. The systems and methodologies of each Kalām School are shaped within the framework of the knowledge understanding of that Kalām School. The approach of the Kalām schools to theological issues and their provision of judgments are determined by reaching the truth (haqīqah) knowledge, what they accept as knowledge and what they do not accept. For this reason, the subject of knowledge takes its primary place in the works written on the Kalām. This situation put forth the importance of knowledge in the Kalām. Aḍud al-Dīn al-Ījī(d. 756/1355), one of the predecessors (muta’akhkhirūn) Ash’arītheologians, is one of the Kalām scholar dealing with and clarifying the subject of knowledge. Al-Ījī is considered one of the leading figures of the post- Gazzālī Philosophical Kalām. Al-Ījī, who devoted his work Kitāb alMawāqif to creating his own Kalām methodology and striving to determine a method in theological (Kalām) issues, allocated the introduction of this work to the subject of knowledge. Al-Ījī, who tries to produce a ultimate theory of knowledge by taking advantage of the classical Ash’arī tradition on knowledge, tried to form his own theory by revealing past mistakes and deficiencies in knowledge. It can be said that the Kalām started with knowledge. However, it is known that there is no consensus among theologians about the definition of knowledge. While Mu’tazilî scholars argue that knowledge is a belief, Ash’arī scholars argue that knowledge is an adjective (sifat), whereas Islamic philosophers claim that knowledge is a intellectual entity. Al-Ījī accepts that knowledge is an adjective. According to Al-Ījī, knowledge is the relation/relative of the knowing to the known in a situation. In other words, knowledge is an adjective that exists and attaches itself to something. This adjective distinguishes itself from other information where it exists. In doing so, carried out in a manner based on tradition, not depending on a cause – effect relationship. Al-Ījī maintains that it is possible to obtain absolute knowledge. The classification of knowledge made by kalāmists in order to obtain absolute knowledge will help to understand what knowledge is. The kalāmists divided knowledge into eternal and hādith knowledge and stated that the eternal knowledge is the knowledge of Allah and the hādith knowledge is the knowledge of the created ones. On the other hand, al-Ījī constitutes his theory of knowledge based on hādith knowledge. Because the eternal knowledge is the knowledge of Allah, there is no necessity and acquirement. According to al-Ījī, “hādith knowledge” is divided into two parts as “darūrī/necessary knowledge” and “kasbī/acquired knowledge”. Al-Ījī, who makes extensive statements about necessary knowledge, does not enter detailed explanations about the acquired knowledge and expresses that the knowledge is only possible with the observing, and provides naẓarī (theoretical) knowledge in the majority of his work as a equivalent to “darūrī knowledge”. Adhering to this classification on knowledge made by the theologians before him, al-Ījī has applied the definition of knowledge -he put forward in the final analysis- to darūrī knowledge and naẓarī knowledge. According to him, due to the existential/ontological structure of human beings, darūrī knowledge is the knowledge brought from birth, that is, adjectives of human. Acquiring darūrī knowledge is not within the power of man. On the other hand, naẓarī knowledge depends entirely on the power of man. It is the knowledge that a person obtains through evidence by using some means. Naẓarī knowledge is an adjective of people having intellectual ability and using their intellectual faculties. In this paper, Aḍud al-Dīn al-Ījī’s description of knowledge and his approach to types of knowledge within the framework of this description will be discussed and his knowledge theory will be examined in detail.